Good Science

In a new study, researchers at the University of California San Diego investigate why hair is incredibly strong and resistant to breaking. The findings could lead to the development of new materials for body armour and help cosmetic manufacturers create better hair care products.

Hair has a strength to weight ratio comparable to steel. It can be stretched up to one and a half times its original length before breaking. “We wanted to understand the mechanism behind this extraordinary property,” said Yang (Daniel) Yu, a nanoengineering Ph.D. student at UC San Diego and the first author of the study.

“Nature creates a variety of interesting materials and architectures in very ingenious ways. We’re interested in understanding the correlation between the structure and the properties of biological materials to develop synthetic materials and designs based on nature that have better performance than existing ones,” said Marc Meyers, a professor of mechanical engineering at the UC San Diego Jacobs School of Engineering and the lead author of the study.

In a study published online in the journal Materials Science and Engineering C, researchers examined at the nanoscale level how a strand of human hair behaves when it is deformed, or stretched. The team found that hair behaves differently depending on how fast or slow it is stretched. The faster hair is stretched, the stronger it is. “Think of a highly viscous substance like honey,” Meyers explained. “If you deform it fast it becomes stiff, but if you deform it slowly it readily pours.”

Hair consists of two main parts, the cortex which is made up of parallel fibrils and the matrix, which has an amorphous (random) structure. The matrix is sensitive to the speed at which hair is deformed, while the cortex is not. The combination of these two components Yu explained, is what gives hair the ability to withstand high stress and strain.

And as hair is stretched, its structure changes in a particular way. At the nanoscale, the cortex fibrils in hair are each made up of thousands of coiled spiral-shaped chains of molecules called alpha helix chains. As hair is deformed, the alpha helix chains uncoil and become pleated sheet structures known as beta sheets. This structural change allows hair to handle up a large amount deformation without breaking.

This structural transformation is partially reversible. When hair is stretched under a small amount of strain, it can recover its original shape. Stretch it further, the structural transformation becomes irreversible. “This is the first time evidence for this transformation has been discovered,” Yu said.

“Hair is such a common material with many fascinating properties,” said Bin Wang, a UC San Diego PhD alumna and co-author on the paper. Wang is now at the Shenzhen Institutes of Advanced Technology in China continuing research on hair.

The team also conducted stretching tests on hair at different humidity levels and temperatures. At higher humidity levels, hair can withstand up to 70 to 80 percent deformation before breaking. Water essentially “softens” hair, it enters the matrix and breaks the sulfur bonds connecting the filaments inside a strand of hair. Researchers also found that hair starts to undergo permanent damage at 60 degrees Celsius (140 degrees Fahrenheit). Beyond this temperature, hair breaks faster at lower stress and strain.

“Since I was a child I always wondered why hair is so strong. Now I know why,” said Wen Yang, a former postdoctoral researcher in Meyers’ research group and co-author on the paper.

The team is currently conducting further studies on the effects of water on the properties of human hair. Moving forward, the team is investigating the detailed mechanism of how washing hair causes it to return to its original shape.

Full paper: “Structure and mechanical behaviour of human hair.” Authors of the study are: Yang Yu, Wen Yang, Bin Wang and Marc André Meyers, all of UC San Diego.

When the Deepwater Horizon drilling pipe blew out seven years ago, beginning the worst oil spill in U.S. history, those in charge of the recovery discovered a new wrinkle: the millions of gallons of oil bubbling from the sea floor weren’t all collecting on the surface where it could be skimmed or burned. Some of it was forming a plume and drifting through the ocean under the surface.

Now, scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have invented a new foam, called Oleo Sponge, that addresses this problem. The material not only easily absorbs oil from water, but is also reusable and can pull dispersed oil from the entire water column — not just the surface.

“The Oleo Sponge offers a set of possibilities that, as far as we know, are unprecedented,” said co-inventor Seth Darling, a scientist with Argonne’s Center for Nanoscale Materials and a fellow of the University of Chicago’s Institute for Molecular Engineering.

We already have a library of molecules that can grab oil, but the problem is how to get them into a useful structure and bind them there permanently.

The scientists started out with common polyurethane foam, used in everything from furniture cushions to home insulation. This foam has lots of nooks and crannies, like an English muffin, which could provide ample surface area to grab oil; but they needed to give the foam a new surface chemistry in order to firmly attach the oil-loving molecules.

Previously, Darling and fellow Argonne chemist Jeff Elam had developed a technique called sequential infiltration synthesis, or SIS, which can be used to infuse hard metal oxide atoms within complicated nanostructures.

After some trial and error, they found a way to adapt the technique to grow an extremely thin layer of metal oxide “primer” near the foam’s interior surfaces. This serves as the perfect glue for attaching the oil-loving molecules, which are deposited in a second step; they hold onto the metal oxide layer with one end and reach out to grab oil molecules with the other.

The result is Oleo Sponge, a block of foam that easily adsorbs oil from the water. The material, which looks a bit like an outdoor seat cushion, can be wrung out to be reused — and the oil itself recovered.

At tests at a giant seawater tank in New Jersey called Ohmsett, the National Oil Spill Response Research & Renewable Energy Test Facility, the Oleo Sponge successfully collected diesel and crude oil from both below and on the water surface.

“The material is extremely sturdy. We’ve run dozens to hundreds of tests, wringing it out each time, and we have yet to see it break down at all,” Darling said.

Oleo Sponge could potentially also be used routinely to clean harbors and ports, where diesel and oil tend to accumulate from ship traffic, said John Harvey, a business development executive with Argonne’s Technology Development and Commercialization division.

Elam, Darling and the rest of the team are continuing to develop the technology.

“The technique offers enormous flexibility, and can be adapted to other types of cleanup besides oil in seawater. You could attach a different molecule to grab any specific substance you need,” Elam said.

The team is actively looking to commercialise the material, Harvey said; those interested in licensing the technology or collaborating with the laboratory on further development may contact partners@anl.gov.

Argonne scientists Anil Mane, Joseph Libera and postdoctoral researcher Edward Barry also contributed to the development of the Oleo Sponge. Preliminary results were published in a study in the Journal of Materials Chemistry A, titled “Advanced oil sorbents using sequential infiltration synthesis.”

Researchers at Karolinska Institutet and KTH Royal Institute of Technology in Sweden have contributed to a recent discovery that the heart is filled with the aid of hydraulic forces, the same as those involved in hydraulic brakes in cars. The findings, which are presented in the journal Scientific Reports, open avenues for completely new approaches to the treatment of heart failure.

The mechanisms that cause blood to flow into the ventricles of the heart during the filling, or diastolic, phase are only partly understood. While the protein titin in the heart muscle cells is known to operate as a spring that releases elastic energy during filling, new research at Karolinska Institutet and KTH suggests that hydraulic forces are equally instrumental.

Hydraulic force, which is the pressure a liquid exerts on an area, is exploited in all kinds of mechanical processes, such as car brakes and jacks. In the body, the force is affected by the blood pressure inside the heart and the size difference between the atria and ventricles. During diastole, the valve between the atrium and the ventricle opens, equalising the blood pressure in both chambers. The geometry of the heart thus determines the magnitude of the force. Hydraulic forces that help the heart’s chambers to fill with blood arise as a natural consequence of the fact that the atrium is smaller than the ventricle.

Using cardiovascular magnetic resonance (CMR) imaging to measure the size of both chambers during diastole in healthy participants, the researchers found that the atrium is smaller effectively throughout the filling process.

“Although this might seem simple and obvious, the impact of the hydraulic force on the heart’s filling pattern has been overlooked,” says Dr. Martin Ugander, a physician and associate professor who heads a research group in clinical physiology at Karolinska Institutet. “Our observation is exciting since it can lead to new types of therapies for heart failure involving trying to reduce the size of the atrium.”

Heart failure is a common condition in which the heart is unable to pump sufficient quantities of blood around the body. Many patients have disorders of the filling phase, often in combination with an enlarged atrium. If the atrium gets larger in proportion to the ventricle, it reduces the hydraulic force and thus the heart’s ability to be filled with blood.

“Much of the focus has been on the ventricular function in heart failure patients,” says Dr. Elira Maksuti at KTH’s Medical Imaging Unit and recent PhD from KI’s and KTH’s joint doctoral programme in medical technology. “We think it can be an important part of diagnosis and treatment to measure both the atrium and ventricle to find out their relative dimensions.”

Researchers in Sweden are planning the clinical trial of a new treatment for nonalcoholic fatty liver disease and type 2 diabetes which harnesses liver cells’ own ability to burn accumulated fats.

In a study involving 86 people with varying degrees of fatty liver disease, researchers from KTH Royal Institute of Technology’s Science for Life Laboratory (SciLifeLab) research center and Gothenburg University found that the liver has the ability to burn up accumulated fats. The researchers propose a mixture of substances that will set this process in motion.

One of the most common chronic liver problems in the world, the accumulation of fat in the liver or hepatic steatosis, is the key characteristic of non-alcoholic fatty liver disease (NAFLD). It is linked to obesity, insulin resistance, type 2 diabetes and cardiovascular diseases. Up to 30 percent of subjects with NAFLD develop non-alcoholic steatohepatitis (NASH) in which hepatic inflammation and scarring can lead to cirrhosis and liver cancer.

The researchers mapped the metabolic changes caused by accumulated fat in 86 patients’ liver cells, and combined this data with an analysis of a genome-scale model of liver tissue. Doing so enabled them to identify the precise metabolic changes individual patients’ liver cells undergo due to fat.

The results were published in Molecular Systems Biology.

Lead author Adil Mardinoglu, a systems biologist at KTH and SciLifeLab fellow, is one of the researchers who had earlier established a connection between NAFLD and low levels of the antioxidant, glutathione (GSH). A proof of concept test showed that accumulated liver was burned off by treating human subjects with a “cocktail” that increases oxidation of fat and synthesis of the antioxidants.

Mardinoglu says the team’s metabolic modeling approach, which relied on data from Swedish-based Human Protein Atlas effort, can be used for a number of chronic liver diseases.

Based on the results from the study, an improved intervention using a portfolio of substances has been designed. “This mixture can potentially decrease the amount of the fat accumulated in the liver,” Mardinoglu says. “There is no such drug available at present and we are planning for further clinical trials later this year.”

The approach combines systems biology and clinical medicine in a manner not previously done. “The results are exciting, and we have now designed a mixture of substances that will boost the oxidation of fat and generate antioxidants in the liver tissue,” says senior co-author Jan Borén from University of Gothenburg.

The researchers believe that the mixture of substances could also be used to treat accumulated liver fat due to alcoholic fatty liver disease and type 2 diabetes. “Considering NAFLD and diabetes are common conditions that regularly co-exist and can act synergistically to drive adverse outcomes, such a mixture of substances might also be used in the treatment of subjects with diabetes,” says co-author, Ulf Smith of University of Gothenburg.

Mathias Uhlén, director of the Human Protein Atlas project and co-author of the paper, says: “I am extremely pleased that the resource created through the Human Protein Atlas effort has been used in the analysis of clinical data obtained from NAFLD patients and that this analysis has led to the design of a mixture of substances that can be used for treatment of this clinically important patient group.

The WVU Reed College of Media, in collaboration with computer science students and faculty at the WVU Benjamin M. Statler College of Engineering and Mineral Resources, is hosting an artificial intelligence (AI) course at its Media Innovation Center that includes two projects focused on using AI to detect and combat fake news articles.

Students in the senior-level computer science elective course are working in teams to develop and implement their own AI programs under the instruction of Don McLaughlin, research associate and retired faculty member of the Lane Department of Computer Science and Electrical Engineering.

Stephen Woerner, a computer science senior, is on one of the teams charged with creating a system that detects fake news articles. His team’s approach utilizes a machine learning system to analyze text and generate a score that represents each article’s likeliness that it is fake news. Woerner added that this score is accompanied by a breakdown that explains the rating and provides transparency.

“Artificial intelligence can have all the same information as people, but it can address the volume of news and decipher validity without getting tired,” Woerner said. “People tend to get political or emotional, but AI doesn’t. It just addresses the problem it’s trained to combat.”

This collaboration with the computer science course serves as an example of the Media Innovation Center’s mission to support initiatives, projects, research and curriculum innovations that intersect its work in technology, media and information networks.

“Fake news isn’t just a media problem,” said the Center’s Creative Director Dana Coester. “It’s also a social and political problem with roots in technology. Solving that problem requires collaborating across disciplines.”

McLaughlin says working at the Center has helped his students this semester, as it suggests a more creative atmosphere than classrooms he’s used in the past.

“I’ve taught this course before, but the students seem to be more enthused this time. We appreciate the space and the breakout areas available for team collaboration here at the Center,” said McLaughlin. “Those amenities are valuable in a university environment.”

Each team will demonstrate their completed AI project during the last week of classes at the Media Innovation Center located in the Evansdale Crossing building.

Of the 78 million tons of plastic used for packaging, just 2 percent actually gets recycled and re-used in a similar way.

Nearly a third is leaked into the environment, around 14 percent is used in incineration and/or energy recovery, and about 40 percent winds up in landfills.

One of the problems: Polyethylene (PE) and polypropylene (PP), which account for two-thirds of the world’s plastics, have different chemical structures and thus cannot be repurposed together. Or, at least, an efficient technology to meld these two materials into one hasn’t been available in the 60 years they’ve both been on the market.

That could change with a discovery out of Coates’ lab. Geoffrey Coates, a professor of chemistry and chemical biology at Cornell University and his group have collaborated with a group from the University of Minnesota to develop a multiblock polymer that, when added in small measure to a mix of the two otherwise incompatible materials, create a new and mechanically tough polymer.

The two groups’ work is detailed in a paper, “Combining polyethylene and polypropylene: Enhanced performance with PE/iPP multiblock polymers,” published online in Science.

James Eagan, a postdoctoral researcher in Coates’ group, is lead author of the paper. Other collaborators included researcher Anne LaPointe and former visiting scientist Rocco DiGirolamo.

Scientists for years have tried to develop a polymer that does what Coates, LaPointe and Eagan have achieved. By adding a miniscule amount of their tetrablock (four-block) polymer, with alternating polyethylene and polypropylene segments, the resultant material has strength superior to diblock (two-block) polymers they tested.

In their test, two strips of plastic were welded together using different multi-block polymers as adhesives, then mechanically pulled apart. While the welds made with diblock polymers failed relatively quickly, the weld made of the group’s tetrablock additive held so well that the plastic strips broke instead.

“People have done things like this before,” Coates said, “but they’ll typically put 10 percent of a soft material, so you don’t get the nice plastic properties, you get something that’s not quite as good as the original material.”

“What’s exciting about this,” he said, “is we can go to as low as 1 percent of our additive, and you get a plastic alloy that really has super-great properties.”

Not only does this tetrablock polymer show promise for improving recycling, Eagan said, it could spawn a whole new class of mechanically tough polymer blends.

“If you could make a milk jug with 30 percent less material because it’s mechanically better, think of the sustainability of that,” he said. “You’re using less plastic, less oil, you have less stuff to recycle, you have a lighter product that uses less fossil fuel to transport it.”

Consumers say supermarket tomatoes lack flavour, so a University of Florida researcher led a global team on a mission to identify the important factors that have been lost and put them back into modern tomatoes.

In a study published in the journal Science, Harry Klee, a professor of horticultural sciences with UF’s Institute of Food and Agricultural Sciences, identifies the chemical combinations for better tomato flavour.

“We’re just fixing what has been damaged over the last half century to push them back to where they were a century ago, taste-wise,” said Klee, stressing that this technique involves classical genetics, not genetic modification. “We can make the supermarket tomato taste noticeably better.”

Step one was to find out which of the hundreds of chemicals in a tomato contribute the most to taste.

Modern tomatoes lack sufficient sugars and volatile chemicals critical to better flavour, Klee said. Those traits have been lost during the past 50 years because breeders have not had the tools to routinely screen for flavour, he said.

To help, researchers studied what they call “alleles,” the versions of DNA in a tomato gene that give it its specific traits. Klee likened the concept to DNA in humans. Everyone has the same number of genes in their DNA, but a particular version of each gene determines traits such as height, weight and hair colour.

“We wanted to identify why modern tomato varieties are deficient in those flavour chemicals,” Klee said. “It’s because they have lost the more desirable alleles of a number of genes.”

Scientists then identified the locations of the good alleles in the tomato genome, he said. That required what’s called a genome-wide assessment study. There, scientists mapped genes that control synthesis of all the important chemicals. Once they found them, they used genetic analysis to replace bad alleles in modern tomato varieties with the good alleles, Klee said.

The U.S. is second only to China in worldwide tomato production, according to the U.S. Department of Agriculture. Florida and California account for two-thirds to three-fourths of all commercially produced fresh-market tomatoes in the U.S. Florida growers produce 33,000 acres of tomatoes worth $437 million annually as of 2014, according to UF/IFAS economic research.

Because breeding takes time, and the scientists are studying five or more genes, Klee said the genetic traits from his latest study may take three to four years to produce in new tomato varieties.